Hey @forums2012,
Everyone who uses Keyboard Maestro should have a keyboard-driven Kill-All-Macros Macro.
I have mine bound to ⇧⌃⌥⌘K, which is very, very fast for me to activate.
Hey @peternlewis – I don't see a way to cancel a specific macro from another macro with either a Keyboard Maestro action or via AppleScript.
If I'm missing something please enlighten me – otherwise please think about adding that as a feature.
-Chris